Vanadium(IV and V) Complexes ContainingSNO (Dithiocarbonylhydrazone; Thiosemicarbazone) Donor Sets

Abstract

The VO2+ complexes [VOCl(ONS)] (3) and [VO(ONS)′] (4), and the VO3+ complexes [VO(OEt)(ONS)′] (5) {ONS = (R)-salicylaldehyde thiosemicarbazonate(1−) R = 5,6-C4H4 (3a) or 3-OMe (3b); (ONS)′ = (R)-salicylaldehyde[benzylmercaptothiocarbonylhydrazonate(2−)], R = H, (4a/5a) or 3-OMe (4b/5b)} have been prepared and characterised by IR, EPR, 1H-, and 51V-NMR spectroscopy. In (S)-sBuOH, 4a converts to [VO{(S)-OsBu}(ONS)′] (5c) and [VO(OH)(ONS)′] (or a condensation product thereof). Solutions of 5c show three 51V NMR signals, two of which are due to two diastereomers. The EPR spectra of 3 and 4 in THF reveal the presence of octahedral species in solution. The crystal and molecular structures of complexes 3a·OCMe2, 5a, and 5b have been obtained, revealing basically a tetragonal pyramid, and coordination of the sulfur function in the thiocarbonyl (3) or enethiolate mode (5). The relevance of the compounds to bioinorganic aspects is addressed.